Patent GB-760700-A (GB)
Title: Visual display apparatus for displaying numerical factors and their computed difference
IPC: G06F7/42
Filed: 1953-09-28
Abstract: 760,700. Digital electric calculating-apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. Sept. 28, 1953 [Oot. 1, 1952], No. 26589/53. Class 106 (1). In visual display apparatus comprising a pattern-controlled emitter unit having means for generating potentials representing the components of a succession of different character outlines, and cathode-ray tube display devices having deflector plates for receiving the potentials and tracing the corresponding characters, character selecting means, arranged to make the display devices active when the generated potentials represent selected characters, are connected to accumulating means adapted to receive numerical factors through two manually-operable keyboards and to compute the difference between them, both the factors and their difference being displayed. The display system illustrated in Fig. 1 comprises separate units electrically interconnected, including a two-section keyboard unit for the two factors H, F, a computer unit for obtaining the difference between the factors and determining which is the greater, and a scanning and timing unit which controls cathode-ray tube indicator units some of which may be remotely located. The factors H and F are taken to be 5-digit decimal numbers with 0 always in the units and tens positions, and in each indicator unit, Fig. 6, the factors and their difference are shown on cathode-ray tubes 119H, 119F and 120 respectively, the " 0's " in the first two positions being indicated by corresponding lights 123H, 123F and 124. Light 121H or 121F is lit according to whether H or F is the greater. Further cathode-ray tubes 147H and 147F are used to indicate against a scale on a masking plate 10 the time that has elapsed since the setting up of H and F respectively. A circuit diagram of the system is given (Figs. 7A-F, not shown). Keyboard unit. Each section comprises three banks of tens keys such as 56, Fig. 2, each of which closes contacts when depressed. A depressed key is released by left-hand movement of latch bar 58 either by depression of a further key in the same bank or by energization of solenoid 61. Such solenoids are energized when reset switches HS, FS, Fig. 1, are operated, this operation also interrupting the display on the indicator units. Scanning and timing unit; computer unit. The pattern emitter is similar to that described in Specification 543,977, [Group XXXVIII], and comprises a transparent rotating disc 64, Fig. 4, with two opaque concentric tracks each divided into ten segments and associated with scanning g means comprising a lamp 69, lens system 70 and a photo-cell such as 71X. The signals from the photo-cells are amplified and applied to the X- and Y-deflecting plates of the cathode-ray tube's 119H, 119F and 120, Fig. 6, to trace the characters 0 to 9 in succession, the required character being selected by the timed switching on of the beam under control of one of ten commutators 94, Fig. 4. The keyboard contacts energize relays according to a biquinary code and contact networks of these relays selectively connect lines from the commutators to potentiometers connected to the cathode-ray tube control grids. In the difference-computing networks, which are similar to the apparatus described in Specification 629,621, the amount F is represented in nines complement form. A furthermost significant - carry - detecting contact network energizes a relay 202 (not shown), if H is greater than F; this relay, as well as controlling lamps 121H, 121F, shifts contacts in the commutator lines whereby the difference is always represented in true form. Elapsed time indications. These are given by devices similar to that described in U.S.A. Specification 2,517,987, each including a motor which is actuated as soon as a key in the highest order of the corresponding keyboard section is depressed, and rotates a shaft to drive the arm of a potentiometer, thus varying the amplitude of a wave applied by an oscillator circuit through rectifying means to the X- deflecting plates of the cathode-ray tube 147H or 147F. This causes a vertical line on the screen, Fig. 6, produced by a varying voltage applied to the Y-plates, to move from left to right at a uniform rate. Specification 543,513, [Group XXXVIII], also is referred to.